Map<String, Integer> map = Maps.newHashMap();
    return Multimaps.forMap(map).asMap();
  }

  @Override
  protected Map<String, Collection<Integer>> makePopulatedMap() {
    Map<String, Integer> map = Maps.newHashMap();
    map.put("foo", 1);
    map.put("bar", 2);
    map.put("cow", 3);
    return Multimaps.forMap(map).asMap();
  }

  @Override
  public void testEntrySetRemoveAllNullFromEmpty() {

        for (int i = 0; i < objectsNum; i++) {
          objects.add(new Object());
        }

        Iterable<?> locks = striped.bulkGet(objects);
        assertTrue(Ordering.natural().onResultOf(Functions.forMap(indexByLock)).isOrdered(locks));

        // check idempotency
        Iterable<?> locks2 = striped.bulkGet(objects);
        assertEquals(Lists.newArrayList(locks), Lists.newArrayList(locks2));
      }
    }

        for (int i = 0; i < objectsNum; i++) {
          objects.add(new Object());
        }

        Iterable<?> locks = striped.bulkGet(objects);
        assertTrue(Ordering.natural().onResultOf(Functions.forMap(indexByLock)).isOrdered(locks));

        // check idempotency
        Iterable<?> locks2 = striped.bulkGet(objects);
        assertEquals(Lists.newArrayList(locks), Lists.newArrayList(locks2));
      }
    }